Passenger vehicles are often provided with at least one sacrificial crash protection device mounted between the bumper and the structural frame of the vehicle. Such devices are sometimes referred to in the art as ‘crush cans’ or ‘crash boxes’. Crash boxes are designed to absorb energy from the impact of a low speed traffic collision by controlled permanent deformation, or ‘crushing’. This reduces the amount of energy that is transferred to the structural frame of the vehicle and minimises damage to other components of the vehicle, especially in low speed impacts.
A typical crash box takes the form of a tapered tube having its major axis running parallel to the longitudinal centreline of the vehicle. The tube is wider where it is mounted to the structural frame of the vehicle and has a relatively narrow distal end where it is connected to the bumper. The cross-section of the tube can be almost any shape, but is typically a rectangle or circle.
A tapered tube is effective at absorbing energy from impacts along its major axis. However, even at small angles of inclination the crash box may bend or buckle about the longitudinal axis rather than crush and collapse along its longitudinal axis, making it less effective at absorbing energy. It would therefore be beneficial to design an energy absorbing device for a vehicle that is capable of more effectively absorbing energy from impacts across a range of angles.